I don't run this with elevated privileges but I set /proc/sys/kernel/kptr_restrict to 0. Setting that does require elevated privileges.
If that's not acceptable, the only fix I can think of is to make that event mapping threshold percentage a parameter to create_gcov and pass something low enough. 80% instead of the current threshold of 95% should work, although it's a bit fragile. Eugene -----Original Message----- From: Sam James <s...@gentoo.org> Sent: Friday, June 30, 2023 1:59 AM To: Richard Biener <richard.guent...@gmail.com> Cc: Eugene Rozenfeld <eugene.rozenf...@microsoft.com>; gcc-patches@gcc.gnu.org Subject: [EXTERNAL] Re: [PATCH] Collect both user and kernel events for autofdo tests and autoprofiledbootstrap [You don't often get email from s...@gentoo.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> writes: > On Fri, Jun 30, 2023 at 7:28 AM Eugene Rozenfeld via Gcc-patches > <gcc-patches@gcc.gnu.org> wrote: >> >> When we collect just user events for autofdo with lbr we get some >> events where branch sources are kernel addresses and branch targets >> are user addresses. Without kernel MMAP events create_gcov can't make >> sense of kernel addresses. Currently create_gcov fails if it can't >> map at least 95% of events. We sometimes get below this threshold with just >> user events. The change is to collect both user events and kernel events. > > Does this require elevated privileges? Can we instead "fix" create_gcov here? Right, requiring privileges for this is going to be a no-go for a lot of builders. In a distro context, for example, it means we can't consider autofdo at all.
